HELIOS IV is a balloon payload that flew on the HASP platform in September, 2015. The payload's mission was to prove the viability of solar observation on a high altitude balloon platform. Currently, all solar observation is done either from the ground or from orbiting satellites; however, ground observations are subject to extensive atmospheric interference and satellites are extremely expensive. Placing a solar observatory on a high altitude balloon platform mitigates 99.5% of the atmospheric interference, but does so at a fraction of the cost of actually placing it into orbit.

HELIOS uses photodiodes, or light sensors, and a small field of view camera to determine its position relative to the sun and uses two stepper motors to turn towards the sun. It utilizes two cameras: the first, with a field of view of approximately 20°, is used for in-flight image analysis and solar tracking, and the second, with a field of view of approximately 100°, is used for post-flight analysis.

In August, HELIOS traveled to the Columbia Scientific Balloon Facility in Texas to integrate with the HASP platform. In Septemer, the platform, carrying HELIOS and eleven other payloads from universities across the country, including SIMBA, launched from Ft. Sumner, New Mexico. HELIOS accuratly tracked the sun throughout flight, capturing nearly 7,000 sucessful images of the sun and fullfulling its mission of proving the viability solar observation on a high altitude balloon platform.

One of nearlly 7000 sucessful images

The HELIOS IV mission offically ended in December of 2015 when the team finsihed analyzing flight data. The HELIOS IV payload will be modified to support additional science missions in the next iteration of the project, HELIOS V, which will fly in the fall of 2016.